The following abbreviations are herewith defined, at least some of which are referred to in the ensuing description of the prior art and the present invention.    AN Access Node    CC Continuity Check    CO Central Office    DSLAM Digital Subscriber Line Access Multiplexer    FDB Forwarding Database    GDA Group Destination Address    IGMP Internet Group Management Protocol    IP Internet Protocol    IPTV Internet Protocol Television    IO Intermediate Office    MAC Media Access Control    MEP Maintenance End Point    MIP Maintenance Intermediate Point    RGW Residential Gateway    SAI Service Area Interface    SHE Super Headend    SNMP Simple Network Management Protocol    STB Set-Top Box    TV Television    TLV Type Length Value    VHO Video Hub Office    VLAN Virtual Local Area Network    VOD Video-On-Demand
A diagnostic tool is needed today that can be used to troubleshoot a multicast connectivity flow fault along a path between a given source (source MEP) and a given destination (destination MEP) within a layer 2 aggregation network. The multicast connectivity flow fault occurs when a member/user wants to be a part of a multicast group and has issued an IGMP Join from the destination MEP towards the source MEP requesting to join that multicast group but for whatever reason does not become part of that particular multicast group. This can happen if the IGMP Join was dropped or not updated properly by one of the intermediate nodes/bridges (MIPs) located between the source MEP and the destination MEP. For example, this may happen if: (1) the IGMP Join was dropped by an intermediate node due to an overflow; (2) the IGMP proxy function within an intermediate node did not work properly; (3) the forwarding database (FDB) within an intermediate node was not properly updated; or (4) the FDB overflowed within an intermediate node. In such a situation, the layer 3 multicast could still be functional even though there is a problem at layer 2.
In one application, an IPTV network (which is a layer 2 aggregation network) can suffer from this problem when a customer does not receive a particular television channel (which is part of a particular multicast group) even though they switched to that particular television channel (issued an IGMP Join) and they can still receive and watch other television channels. In this case, the customer would call a customer service representative and the representative would have to pin-point the location of the multicast connectivity flow fault within the IPTV network. The customer service representative would do this by interacting with a console to log into a bridge (via a serial port, SNMP over IP, web server over IP) and retrieve the status of individual intermediate nodes. Plus, the customer service representative would have to manually inspect the status of each intermediate node one-by-one by browsing large databases (FDBs) to diagnose and correct the multicast connectivity flow fault. This process is very tedious and not very efficient. Accordingly, there is a need for a new diagnostic tool and a method which can be used to effectively and efficiently troubleshoot a multicast connectivity flow fault within a layer 2 aggregation network (IPTV network). This need and other needs are solved by the diagnostic tool and method of the present invention.